Browse Prior Art Database

Servo Pattern for Hard Disk Drive

IP.com Disclosure Number: IPCOM000111515D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Kigami, Y: AUTHOR [+2]

Abstract

Disclosed is a servo pattern for Hard Disk Drive employing an embedded sector servo. The disclosed pattern consists of a digital block and an analog block preceding the former one. With this pattern, the amount of position error can be calculated in a short time.

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Servo Pattern for Hard Disk Drive

      Disclosed is a servo pattern for Hard Disk Drive employing an
embedded sector servo.  The disclosed pattern consists of a digital
block and an analog block preceding the former one.  With this
pattern, the amount of position error can be calculated in a short
time.

      Hard Disk Drive with embedded sector servo controls the
position of the head using the position error information acquired
from the servo pattern.  The Figure shows an example of the servo
pattern disclosed in this article.

      A mark (1) indicates a starting position of a servo pattern.  A
demodulator recognizes the starting point of the pattern by this mark
(1).  An analog block (2) is usable to get a precise position error.
To demodulate block (2), some amount of time must be required for
analog-to-digital conversion.  A digital block (3) is usable to get
the rough information of the position of the head.  The information,
such as cylinder number, is recorded in this block (3).  By placing
the block (2) ahead of block (3), the demodulator can convert the
analog information obtained from the block (2) to digital one while
reading the information from the block (3).

      With this servo pattern, the Hard Disk Controller can get the
head postion error in a short period from the demodulator.  So the
write operation to an illegal position can be prevented.